Fundamentals of Heat and Mass Transfer
7th Edition
ISBN: 9780470917855
Author: Bergman, Theodore L./
Publisher: John Wiley & Sons Inc
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Chapter 5, Problem 5.64P
A long rod 40 mm in diameter, fabricated from sapphire (aluminum oxide) and initially at a uniform temperature of 800 K, is suddenly cooled by a fluid at 300 K having a heat transfer coefficient of
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quantity.
Example 1/ The roof of an electrically heated home is 6 m long, 8 m
wide, and 0.25 m thick, and is made of a flat layer of concrete whose
thermal conductivity is k 0.8 W/m.°C (Figure. 1-3). The temperatures
of the inner and the outer surfaces of the roof one night are measured to
be 15°C and 4°C, respectively, for a period of 10 hours. Determine the
rate of heat loss through the roof at night.
Concrete roof -
0.25 m
8 m
6 m
4°C
15°C
Figure 1-3 Schematic for Example 1
Q1/ The center to surface
temperature difference in a heat
generating cylindrical rod of 4 m
diameter was 30°C. What is the
difference temperature between
the center and surface in the case
of a sphere of 2 m diameter under
similar conditions? *
Your answer
Q2/ A metal plate of 4mm thickness
(k = 95.5 W/m°C) is exposed to
vapor at 100°C on one side and
cooling water at 25°C on the
opposite side. The heat transfer
coefficients on vapor side and
waterside are 14500 W/m^2°C and
2250 W/m^2 °C respectively.
Determine the overall heat transfer
coefficient *
Your answer
The thermal conductivity of a sheet of rigid, extruded insulation is reported to be k = 0.029 W/m-K. The measured temperature
difference across a 25-mm-thick sheet of the material is T – T2 = 12°C.
(a) What is the heat flux through a 3 m x 3 m sheet of the insulation, in W/m2?
(b) What is the rate of heat transfer through the sheet of insulation, in W?
(c) What is the thermal resistance of the sheet due to conduction, in K/W?
Chapter 5 Solutions
Fundamentals of Heat and Mass Transfer
Ch. 5 - Consider a thin electrical heater attached to a...Ch. 5 - The inner surface of a plane wall is insulated...Ch. 5 - A microwave oven operates on the principle that...Ch. 5 - A plate of thickness 2L, surface area As, mass M,...Ch. 5 - For each of the following cases, determine an...Ch. 5 - Steel balls 12 mm in diameter are annealed by...Ch. 5 - Consider the steel balls of Problem 5.6, except...Ch. 5 - The heat transfer coefficient for air flowing over...Ch. 5 - A solid steel sphere (AISI 1010), 300 mm in...Ch. 5 - A flaked cereal is of thickness 2L=1.2mm. The...
Ch. 5 - The base plate of an iron has a thickness of L=7mm...Ch. 5 - Thermal energy storage systems commonly involve a...Ch. 5 - A tool used for fabricating semiconductor devices...Ch. 5 - A copper sheet of thickness 2L=2mm has an initial...Ch. 5 - Carbon steel (AISI 1010) shafts of 0.1-m diameter...Ch. 5 - A thermal energy storage unit consists of a large...Ch. 5 - Small spherical particles of diameter D=50m...Ch. 5 - A spherical vessel used as a reactor for producing...Ch. 5 - Batch processes are often used in chemical and...Ch. 5 - An electronic device. such as a power transistor...Ch. 5 - Molecular electronics is an emerging field...Ch. 5 - A plane wall of a furnace is fabricated from plain...Ch. 5 - A steel strip of thickness =12mm is annealed by...Ch. 5 - In a material processing experiment conducted...Ch. 5 - Plasma spray-coating processes are often used to...Ch. 5 - The plasma spray-coating process of Problem 5.25...Ch. 5 - A chip that is of length L=5mm on a side and...Ch. 5 - Consider the conditions of Problem 5.27. 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